ACL2-PC::DV

Examples:
(dv 1) -- assign the new current subterm to be the first argument
of the existing current subterm
(dv 1 2) -- assign the new current subterm to be the result of
first taking the 1st argument of the existing
current subterm, and then the 2nd argument of that

For example, if the current subterm is

(* (+ a b) c),

then after (dv 1) it is

(+ a b).

If after that, then (dv 2) is invoked, the new current subterm
will be

b.

Instead of (dv 1) followed by (dv 2), the same current subterm
could be obtained by instead submitting the single instruction
(dv 1 2).

General Form:
(dv &rest naturals-list)

If naturals-list is a non-empty list (n_1 ... n_k) of natural
numbers, let the new current subterm be the result of selecting the
n_1-st argument of the current subterm, and then the n_2-th subterm
of that, ..., finally the n_k-th subterm.

Note:(dv n) may be abbreviated by simply n, so we could have typed
1 instead of (dv 1) in the first example above.

Note: See also dive, which is related to the command pp, in that
the diving is done according to raw (translated, internal form)
syntax. Use the command dv if you want to dive according to the
syntax displayed by the command p.